1. Field of the Invention
The present invention relates to a window made of synthetic resin, and more particularly to a synthetic resin window which is suitable for automative vehicles or the like.
2. Description of the Related Art
A synthetic resin window for automative vehicles is disclosed, e.g., in Japanese Utility Model Application Laid-open Publication No. 61-32,808, as being manufactured by injection molding process. The known synthetic resin window generally includes a window body portion of transparent or semi-transparent synthetic resin, such as polycarbonate or acrylic resin, as well as a frame portion extending along the peripheral edge of the body portion and formed into a predetermined shape which corresponds to flange of a relevant vehicle body panel.
Due to susceptibility of the synthetic resin to scratches or the like damages, the outer surface of the window body portion is generally covered by a hard coated film layer, while the outer surface of the frame portion is covered by an opaque coated layer of a desired color.
For mounting the synthetic resin window onto the flange portion of the vehicle body panel, the frame portion is integrally formed on its inner surface side with bosses to accommodate therein threaded mount members which are to be inserted into corresponding openings in the flange portion and engaged by respective nuts. A satisfactory tight contact between the window and the vehicle body panel can be achieved by a cushioning member of soft or resilient material arranged on regions of the frame portion to be brought into abutment with the vehicle body panel.
The abovementioned known synthetic resin window proved to be advantageous particularly in its reduced weight, but suffers from a problem of significantly low rigidity as compared with conventional inorganic glass windows. Thus, the synthetic resin window as mounted on the vehicle body panel often exhibits undesirable deformation or damage as a result of fastening force or the like.
The required rididity of the synthetic resin window might be realized either by increasing the thickness of the window body portion itself, or by providing reinforcing ribs on the frame portion. However, these solutions are not very suitable from practical viewpoints that an increased thickness of the window body portion would make it almost impossible to achieve a reduced weight of the window as a whole, while provision of the reinforcing ribs on the frame portion more or less results in formation of undesirable sink mark on the outer surface of the frame portion to significantly deteriorate the appearance.